Co-author Giovanni Bianucci of the University of Pisa's
Department of Earth Sciences, told Discovery News it's probable
that the shark attacked the whale as it was "diving, considering
that the bite was on the abdomen"

Bianucci and co-author Phillip Gingerich of the University of
Michigan's Museum of Paleontology and Department of Earth and
Environmental Sciences determined that the shark bit into five of
the whale's ribs, with the most significant damage occurring to
its rear left side.

"The shape and position of these marks make it likely that they
resulted from an individual shark attack," Bianucci said.
"Probably the shark attacked from the rear and the left, an
attack strategy also described for the extant white shark when
attacking seals and sea lions."

The whale may have fought back, because the shark did not
completely consume its target, eventually releasing it either
dead or dying. Over millions of years the whale's body fossilized
prior to being discovered by a shocked stonecutter from Italy who
sliced it into decorative facing stone before realizing what he
had found.

Normally scientists try not to cut such rare specimens, but since
this one was already sliced, the researchers could see important
details, enabling them to identify this as a transitional
land-to-water whale. All whales evolved from a land animal that
gradually started to rest, breed and give birth on land while
feeding in the sea at other times.

Based on skull and skeleton measurements, Aegyptocetus
weighed about 1,400 pounds when it was alive. Its teeth suggest
that it primarily fed on fish.

This species lived in the middle of the great whale's move to
permanent ocean life. That transition started about 55 to 50
million years ago. Modern baleen and toothed whales didn't evolve
until around 30 million years ago.

Bianucci and Gingerich document how the newly found species
displays characteristics of the transition, such as a retained
sense of smell, which is usually lost in aquatic mammal lineages,
the ability to haul itself out of water, and an enhanced ability
to hear, with a better hearing than later and modern whales.

As for why whales chose the all-water life, the researchers
suggest ample food might have been the irresistible draw.
Gingerich explained that the whales probably first engaged in
"scavenging of dead fish on a shoreline, then chasing dying fish
in the water, then pursuing healthy fish farther offshore as well
as the dying, and finally losing all ties to the land and
becoming fully marine."

Anthony Friscia, a researcher in the Department of Integrative
Biology and Physiology at the University of California, Los
Angeles, told Discovery News that "the most amazing thing about
this discovery is the way it (the fossil whale) was found."

"Not only was it fortuitous that it was spotted at all, but the
fact that the skull was already sliced actually made it more
useful," Friscia said, mentioning that the "slicing revealed one
of the more amazing characters of the specimen: the presence of
small, scroll-like bones in the nose, called turbinates, which
speak to the smelling ability of the species."

For those with limestone in homes, it's possible that the stone
contains prehistoric animal fossils like the shark and described
whale, but few see them. Gingerich explained that the fossils
weather away at the same rate as the limestone.

"You have to be looking right at the surface at the right spot to
see that there are bones there," he said.